The statement that best summarizes Darwin's theory of natural selection is D. Organisms best suited to their environment will survive and reproduce. This is becasue let's say some giraffes have short necks and some long necks and their food is leaves on high trees then the long necked giraffes will survive over short necked giraffes because short necked giraffes can't reach for their food and eventually there will be only long necked giraffes left and they will reproduce with other long necked giraffes and make long necked giraffes.
The first, third, and fourth, because igneous, metamorphic, and sedimentary rock phases can all occur.
Answer:
The correct answer would be the pulmonary vein and the superior vena cava.
Pulmonary vein is a blood vessel of pulmonary circulation which carries oxygenated blood from lungs to the left atrium of the heart. Hence, it is rich in oxygen and carries carbon dioxide in the least amount.
In contrast, vena cava is a part of systemic circulation and carries deoxygenated blood from the body to the right atrium of the heart. They are two venae cavae in human beings namely; inferior vena cava (carries blood from lower body) and superior vena cava (carries blood from head, arms and upper body). Hence, it contains maximum carbon dioxide and least oxygen.
Embryo should be the answer